IL6 and neoplasm: Increased serum levels of cytokines and their soluble receptors that are involved in bone degradation (e.g., IL‐6 and IL‐8) and bone formation (e.g., tumor necrosis factor receptor I [TNFRI]) are positively correlated with tumor size and local tumor extent, which is associated with worse overall survival in adult bone sarcoma patients (Rutkowski et al, 2003).